The development of real-time charging technologies creates favorable conditions for an operator to further segment the market into specific sectors. For example, with a real-time charging technology, the operator may formulate multiple monthly packages corresponding to different durations to meet needs of different users. In another example, the operator may divide each day into different time segments according to network utilization status, and set different tariffs for the different time segments. For example, a high tariff is set for a network busy time segment (such as 20:00 to 23:00 everyday); and a low tariff is set, or even no fee is charged, in a network idle time segment (such as 06:00 to 08:00 everyday) (the 24 hour-clock is used throughout this application).
In an existing real-time charging technology, an operation is defined for forcing a user to go offline. If a current service volume available to the user, determined according to the current account balance and the current tariff, is smaller than a service unit requested by the user, all the available service volume is granted to the user as a granted service unit. When it is detected that the service volume used by the user has reached the limit of the granted service unit, the user is forced to go offline. However, the condition for performing the operation of forcing a user to go offline (e.g. when the current service volume available to the user, determined according to the current account balance and the current tariff of the user, is smaller than the service unit requested by the user) may be too simple, and therefore, can result in unexpected consequences under an operator's increasingly complicated charging policies, and various requirements set forth by the increasingly complicated charging policies of the operator can hardly be met. For example, with the existing real-time charging technology, when a user enters from a fee-charging time segment into a fee-free time segment during the use of a service, even if the user's account has a sufficient balance after the user enters the fee-free time segment, the user may still be forced offline after the tariff switching. Such a circumstance is described in detail with reference to FIG. 1.
FIG. 1 is a signaling diagram of an existing real-time charging method 100. In the scenario shown in FIG. 1, for example, 06:00 is a tariff switch point, and the tariff is 1 yuan per megabytes (yuan/M) before the tariff switching and is 0 yuan/M after the tariff switching. At 05:51, the user sends a login request to an access device, and the account balance of the user is 10 yuan at this time.
Step 102: The access device responds to the login request from the user, and sends an access request to an authentication device.
Step 104: The authentication device sends an initial credit control request (CCR {Init}) to a charging device, where the initial credit control request carries a requested service unit (RSU) of 100 M.
The charging device determines a current available service volume according to the current account balance and the current tariff of the user. If the current account balance of the user is 10 yuan, and the current tariff is 1 yuan/M, the current available service volume is determined to be 10 megabytes (M).
Step 106: The charging device sends an initial credit control answer (CCA {Init}) to the authentication device. Because the determined current available service volume 10 M is smaller than the requested service unit of 100 M, a granted service unit (GSU) carried in the CCA {Init} is 10 M, same as the current available service volume. If, on the other hand, the determined current available service volume is larger than or equal to the requested service unit 100 M, the granted service unit carried in the CCA{Init} is the same as the requested service unit, 100 M.
Step 108: The authentication device determines that the granted service unit 10 M carried in the CCA{Init} is smaller than the requested service unit 100 M, and therefore, grants all the 10 M service unit to the user. Specifically, the authentication device sends an access response to the access device. The access response carries a parameter VT=VQ=10 M, where VT is a volume threshold, and VQ is a volume quota. According to the existing technical specifications about real-time charging, the VT being equal to the VQ indicates that the access device should force the user to go offline when the used service unit of the user reaches the 10 M threshold. For ease of description, VT is hereinafter called a granted service unit. If, on the other hand, the granted service unit carried in the CCA{Init} is the requested service unit, such as 100 M, the VT carried in the access response will be set to be close to but smaller than the VQ, so that the access device will send a service volume request again when detecting that the used service unit of the user reaches the VT (that is, close to but not yet reached the VQ). The purpose of such a setting is that: At the time of requesting the charging device to grant a further volume to the user after the used service unit of the user has reached the VT, a small service volume, which equals to a difference between the VQ and the VT, is still available to the user. This avoids the problem that the service is unavailable to the user in the requesting process, where the problem occurs because the charging device is not requested again to grant a service volume to the user until VQ is reached.
Therefore, the purpose of setting the parameter “granted service unit” is to instruct the access device to send a request to the charging device again when the access device detects that the used service unit of the user reaches the granted service unit, where the request is a request for granting a further service volume to the user. In a specific implementation process, VT and VQ may be set according to specific needs. The access response further includes a tariff switch interval (TSI), which is used to indicate a time interval between the current time and the tariff switch point, to prompt the access device to separately report the service volume used before the tariff switch point and the service volume used after the tariff switch point. In FIG. 1, TSI=540 s indicates that the current time is 540 seconds away from the tariff switch point.
Step 110: When the used service unit of the user reaches 10 M, the access device sends an online access request (stop) to the authentication device, where the request carries the used service unit 10 M and indicates that, among the 10 M used service unit, the service volume used after the tariff switch point 06:00 is 1 M, i.e. a volume used after tariff switch (VUATS) is 1 M.
When the used service unit of the user reaches 10 M, the access device forces the user to go offline.
Step 112: The authentication device notifies the used service unit to the charging device through a terminate credit control request (CCR{Term}), where the used service unit is carried in a used service unit (USU) field. According to the existing technical specifications about the real-time charging, after the tariff is switched, two USUs will be reported respectively. A USU (TCU=2) represents the total service volume used in the previous charging cycle, 10 M; and a USU (TCU=1) represents the service volume used after tariff switching in the previous charging cycle, 1 M, where TCU represents tariff change usage.
Afterward, the charging device deducts a fee according to the used service unit. Because the service volume used before 06:00 is 9 M and the tariff before 06:00 is 1 yuan/M, the generated expense is 9 yuan; because the service volume used after 6:00 is 1 M and the tariff after 06:00 is 0 yuan/M, the generated expense is 0 yuan. Therefore, the total deducted fee is 9 yuan, and the user account balance is 1 yuan after the deduction.
Step 114: The charging device sends a terminate credit control answer (CCA{Term}) to the authentication device.
Step 116: The authentication device sends an access response (stop) (Access Response (stop)) to the access device.
As evidently revealed in the foregoing process, at the tariff switch point (06:00), the user uses only a 9 M service volume. Because the tariff before 06:00 is 1 yuan/M, the expense of the user is 9 yuan, and the user account balance at 06:00 is 1 yuan. According to the tariff after the tariff switch point (0 yuan/M), the user can continue using the service generously, the user can continue using the service at least before the fee-free time segment ends. However, according to the existing real-time charging method as shown in FIG. 1, the user will be still forced to go offline after the tariff switch point, even if the user account has a balance and the tariff switch point is followed by a fee-free time segment.